ACTG 392 is a multicenter study (10 subjects per site) to test the effectiveness of a nutrutional supplement containing 40g of wheyprotein and high amounts of cysteine and glutamie compared to a similar isocaloric supplement without added protein or amino acids in HIV positive persons with stable weight loss. The primary endpoint will be change in lean body mass and an important secondary endpoint will be chaning in anto-oxidant status. The GCRC will be used fo rthis project to specially process blood at baseline and study weeks 6 and 12 to prevent oxidation of glutathione and cysteine in plasma which will be measured later.